In recent years, scholars discover that a polypeptide—chlorotoxin (CTX) with a segment composed of 36 amino-acid residues. The CTX has good tumor targetability capable of specifically combining different types of tumor cells such as giloma, sarcoma, colorectal, prostate cancers, etc. Researches show that CTX may be introduced into tumor cells through a matrix metalloproteinases-2 (MMP-2) medium, and MMP-2 is expressed in large quantity on the surface of tumor cells but not on the surface of normal cells. This explains why CTX specifically combines with tumor cells. Meanwhile, researches also show that CTX has a strong toxicity to invertebrates but no toxicity to mammals. At present, CTX modified radioactive treatment medicine 131I-TM-601 is adopted and filed for the approval by FDA and has entered into Phase II clinical trials. Some researches apply CTX and fluorescent dyes for displaying tumors in a surgical process. Therefore, CTX may become a targeting head group with high tumor specificity.
The current research trend aims at chlorotoxin, but the innovation on the folded structure and varied structure of chlorotoxin is poor, and thus restricting the potential of the application of chlorotoxin.